Potentiometric sensor

Abstract

A potentiometric sensor includes an electrochemical half-cell with an inner electrolyte, a pickup electrode contacting the inner electrolyte, a sensor element that, in order to detect measured values, can be brought into contact with a measuring medium and, especially, is immersible in the measuring medium, where the sensor is designed as a composite body that includes an ion-selective component which is in contact with the inner electrolyte.

What is claimed is: 
     
         1 . A potentiometric sensor comprising:
 an electrochemical half-cell, including:
 a housing; 
 an inner electrolyte disposed in the housing; 
 a pickup electrode contacting the inner electrolyte; and 
 a composite body including a porous ceramic substrate and an ion-selective component, wherein the ion-selective component is disposed on the porous ceramic substrate and/or has penetrated pores of the porous ceramic substrate, wherein the ion-selective component is embodied to contact a liquid measuring medium and to be immersible in the liquid measuring medium, 
 wherein the ion-selective component is in contact with the inner electrolyte, and 
 wherein the composite body is clamped or affixed liquid tightly in a wall of the housing. 
   
     
     
         2 . The potentiometric sensor according to  claim 1 , wherein the composite body is clamped or affixed liquid tightly in the wall of the housing by elastomer seals. 
     
     
         3 . The potentiometric sensor according to  claim 2 ,
 wherein the housing has a wall that forms and at least partially encloses a half-cell chamber, wherein the housing has an opening at a front end of the housing;   wherein the inner electrolyte is disposed in the half-cell chamber;   wherein the potentiometric sensor includes a first elastomer seal and a second elastomer seal, wherein the composite body is disposed at the front end of the housing such that the sensor element, the first elastomer seal, and the second elastomer seal seal the opening at the front end of the housing.   
     
     
         4 . The potentiometric sensor according to  claim 3 , wherein the ion selective component is disposed on a side of the porous ceramic substrate facing away from the half-cell chamber. 
     
     
         5 . The potentiometric sensor according to  claim 4 ,
 wherein the housing includes a first tubular part and a second tubular part, wherein the first tubular part includes threads disposed on an outer circumference of the first tubular part and the second tubular part includes threads disposed on an inner circumference of the second tubular part in such a way that the second tubular part can be screwed onto the first tubular part, and   wherein the composite body is positioned between the first and second elastomer seals and is clamped liquid tightly to the housing, when the second tubular part is screwed onto the first tubular part.   
     
     
         6 . The potentiometric sensor according to  claim 1 , wherein the porous ceramic includes zirconium dioxide ceramics, magnesium-stabilized zirconium dioxide ceramics, or yttrium-stabilized zirconium dioxide ceramics. 
     
     
         7 . The potentiometric sensor according to  claim 1 , wherein the ion-selective component includes an ion-selective polymer or a pH membrane glass. 
     
     
         8 . The potentiometric sensor according to  claim 7 , wherein the ion-selective component is a coating on the porous ceramic substrate. 
     
     
         9 . The potentiometric sensor according to  claim 7 , wherein the thermal expansion coefficient of the porous ceramic is adjusted to that of the ion selective component. 
     
     
         10 . The potentiometric sensor according to  claim 1 , further comprising:
 a reference half-cell; and   a measuring circuit,   wherein the measuring circuit is designed to detect a difference in potential between the electrochemical half-cell and the reference half-cell and to output a measuring signal representing the difference in potential.   
     
     
         11 . The potentiometric sensor according to  claim 1 , wherein the ion selective component is in contact with the inner electrolyte via pores of the porous ceramic substrate. 
     
     
         12 . A potentiometric sensor comprising:
 an electrochemical half-cell, including:
 a housing having a wall that forms and at least partially encloses a half-cell chamber, wherein the housing has an opening at a front end of the housing; 
 a composite body including a porous ceramic substrate and an ion-selective component, wherein the ion-selective component is disposed on a first side of the porous ceramic substrate and/or has penetrated pores of the porous ceramic substrate, wherein the ion-selective component is embodied to contact a liquid measuring medium and to be immersible in the liquid measuring medium; 
 a first elastomer seal and a second elastomer seal, wherein the composite body is disposed at the front end of the housing such that the composite body, the first elastomer seal, and the second elastomer seal seal the opening at the front end of the housing, and wherein the ion-selective component faces away from the half-cell chamber; 
 an inner electrolyte disposed in the half-cell chamber; and 
 a pickup electrode contacting the inner electrolyte in the half-cell chamber. 
   
     
     
         13 . The potentiometric sensor according to  claim 12 ,
 wherein the housing includes a first tubular part and a second tubular part, wherein an inner circumference of the second tubular part corresponds to an outer circumference of the first tubular part,   wherein the first tubular part includes threads disposed on the outer circumferences and the second tubular part includes threads disposed on the inner circumference,   wherein the threads of the first tubular part and of the second tubular part are complementary and enable the second tubular part to be screwed onto the first tubular part, and   wherein the second tubular part is embodied to clamp the first elastomer seal, the composite body, and the second elastomer seal to the first tubular part and thereby close and seal the half-cell chamber.   
     
     
         14 . The potentiometric sensor according to  claim 12 ,
 wherein the porous ceramic is zirconium dioxide, magnesium-stabilized zirconium dioxide, or yttrium-stabilized zirconium dioxide.   
     
     
         15 . The potentiometric sensor according to  claim 12 ,
 wherein the ion-selective component includes an ion-selective polymer or a pH membrane glass.   
     
     
         16 . The potentiometric sensor according to  claim 15 , wherein the ion-selective component is a coating on the porous ceramic substrate. 
     
     
         17 . A potentiometric sensor, comprising:
 an electrochemical half-cell, the electrochemical half-cell including:   a housing;   an inner electrolyte disposed in the housing;   a pickup electrode contacting the inner electrolyte; and   a sensor element including a porous ceramic substrate comprising a solid body and an ion-selective component, wherein the ion-selective component is disposed on the porous ceramic substrate and/or has penetrated pores of the porous ceramic substrate, wherein the ion-selective component is embodied to contact a liquid measuring medium and to be immersible in the liquid measuring medium,   wherein the ion-selective component is in contact with the inner electrolyte, and   wherein the sensor element is affixed liquid-tightly in a wall of the housing by elastomer seals, and wherein the sensor element is not materially bonded to the housing wall.